Objective: To analyze the superposition effect of policies in the basic medical insurance, the supplementary insurance and medical assistance in Shanghai, the actual burden of relief object and assistance implementation effect. Methods: Using the data of Shanghai Civil Affairs Bureau to analyze the burden of medical expenses, the effect of medical assistance and the occurrence of catastrophic health expenditure. Results: In 2015, the per capita medical expenses of medical assistance in Shanghai was 17344 yuan, and the patient co-payment accounted for about 27.4% of the total medical expenses. The amount of per capita medical assistant was 2276 yuan, accounting for 48.0%of the co-payment; the co-payment accounted for 14.3% of the total medical expenses with the medical assistant, that was and 13.1percentage point of co-payment decreased. The proportion of catastrophic health expenditure before medical assistant was 27.1% and reduced to 17.2%. Conclusion: The medical assistance was effective in reducing the co-payment and catastrophic proportion in Shanghai, but the medical assistant differed among different population groups. it was suggested all objective of medical assistant should be full covered by basic medical insurance, enhanced the convergence of medical assistant with the basic medical insurance and improve d the level of medical assistant